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Critical Monitoring of Forklift Emissions and Warehouse Ambient Air Quality

Case Study #EX-17-503


E Instruments International’s gas monitoring specialists performed a forklift exhaust gas analysis and an ambient air quality analysis at a Pennsylvania warehouse in which a fleet of propane forklift trucks is operated on a daily basis. The main objectives of these tests were to investigate:

1) The effect that different engine conditions – Idle and Load – have on exhaust gas emissions from propane forklifts, and

2) The effect that forklift emissions have on the ambient air quality of the warehouse.

Exhaust Gas Analysis

Exhaust gas analysis was performed using an E Instruments model F5000-5GAS portable five gas analyzer to measure the concentrations of Carbon Monoxide (CO), Oxygen (O2), Carbon Dioxide (CO2), Hydrocarbons (HC), and Nitric Oxide (NO) for NOx being emitted directly from forklift exhausts. These five gases are typically monitored in order to assess the performance and operating conditions of forklift engines. Minimizing the exhaust gas emissions of CO, HC, and NO from the forklift will result in cleaner combustion emissions, lower fuel consumption, minimized equipment maintenance, and optimized overall forklift performance while reducing warehouse operating costs. This case study will focus on exhaust gases CO and HC.

Ambient Air Quality Analysis

Ambient air quality analysis was performed using an E Instruments model AQ PRO ambient air quality monitor to measure the concentrations of Carbon Monoxide (CO) and Nitrogen Dioxide (NO2), toxic gases found in the air, which likely originated from, and was emitted by, forklift engines. Increased CO levels in the air can cause headaches, fatigue, nausea, and even death in extreme cases for operators working in such environments. NO2 exposure can cause respiratory problems such as wheezing, coughing, colds, flu and bronchitis. Indoor Air Quality analysis was conducted continuously from the Initial Ambient test (no forklift running), Idle Test and Load Test of the forklifts.

Zone A: Initial Test – Forklift Off (T= 0-10 mins)

The quality of the ambient air was tested at various locations throughout the warehouse using the AQ PRO air quality monitor. At the time of these tests, the forklift had not been used for approximately 24 hours.

Exhaust Analysis
CO = 0% and HC = 0ppm

Ambient Air Analysis
CO = 0ppm and NO2 = 0ppm.

This represents ambient air quality baseline values.

Zone B: Forklift Idle – No Load (T= 10-40 mins)

The forklift truck engine was started and an F5000 exhaust gas analyzer was connected to the forklift exhaust pipe using an S-type probe to begin analyzing the engine emissions at Idle condition. The Idle condition refers to the forklift engine running while the vehicle is stationary and without a load. Ambient Air quality was continuously monitored during the truck engine testing using the AQ PRO.

Exhaust Analysis
CO quickly increases from 0 to 0.04%.
HC increases from 0 to ~240ppm.

Ambient Air Analysis
CO increases from 0 to 1ppm.
NO2 increases steadily from 0 to 0.3ppm.

Zone C: Forklift Under Load (T= 40-160 mins)

During the Load condition, the forklift technician engaged the forklift engine throttle, putting a load on the engine.

Exhaust Analysis – CO increases significantly from 0.04% to 0.08%. HC increases from 240ppm to a maximum of 420ppm. This indicates incomplete combustion which leads to increased toxic emissions and increased fuel cost due to unburned fuel.

Ambient Air Analysis – CO increases steadily from 1ppm to 4.5ppm during load test. The CO trend indicates that without proper ventilation, the CO level within the warehouse may reach or exceed the OSHA threshold of 9ppm for CO within 4 hours of forklift load operation resulting in unsafe working conditions. NO2 levels steadily increase from 0.3ppm to over 0.5ppm.

Zone D: Forklift Off (T= 160-200 mins)

The forklift engine was turned off while technicians continued measuring exhaust and ambient air quality.

Exhaust Analysis – CO and HC emissions decrease back to 0% and 0ppm, respectively, after shutting the forklift engine off.

Ambient Air Analysis – CO and NO2 decrease to 0.05ppm and 0.1ppm, respectively, within 30 minutes of shutting off forklift. This indicates that forklift exhaust is directly correlated to CO and NO2 levels in warehouse ambient air. This also suggests that proper ventilation is needed to dissipate exhaust fumes.


1) Forklift exhaust emissions of CO and HC increase significantly when the engine goes from Idle to Load. This indicates incomplete combustion and a potential opportunity for optimizing engine efficiency.

2) Levels of CO and NO2 significantly increase when forklift engines are engaged indicating a decrease in ambient air quality. Concentrations of these gases are dramatically increased when the engine goes from Idle to Load. This suggests the need for periodic monitoring and the implementation of an ambient air quality protocol in order to maintain worker productivity, health and safety.

Strategies for Optimizing Equipment Performance and Worker Safety/Productivity

1) Monitoring Warehouse Equipment Emissions and Efficiency – Periodic monitoring of emissions from diesel forklifts and other equipment that emit toxic gases provides information on each machine’s contribution to air quality, but also on the vehicle’s efficiency. Poor emissions may indicate a malfunction that would require maintenance in order to optimize combustion efficiency & maximize fuel savings, identify and quantify sources that can adversely affect safety and comfort in the work environment, and measure and reduce harmful emissions in the forklift engine exhaust gas.

2) Indoor Air Quality Monitoring – Periodic measurements of air quality at a wide variety of locations of a warehouse provide an understanding of potential safety problems that may be occurring for on the floor personnel. Elevated levels of CO, NOx or other toxic gases will have negative effects on worker productivity and safety.

3) Air Movement/Replacement Strategies to Avoid Toxic Gas Build Up – Ventilation and air movement or replacement plans can reduce toxic gas build up.

4) Implementing a Long-Term Air Quality Optimization Strategy – A long-term air quality optimization strategy that aims to 1) measure and maintain the air quality standards required to run the warehouse, and 2) measure and evaluate the performance of all of the contributing factors to warehouse air quality can improve overall efficiency. A long-term plan standardizes practice, and provides a framework for a successful balance of equipment performance as well as worker safety and productivity.

Warehouse Forklift Emissions and Air Quality Monitoring Solutions: F5000 and AQ PRO

Warehouse indoor air quality and forklift emissions monitoring can be performed using the E Instruments F5000 portable emissions monitor and the AQ Pro Handheld IAQ monitor. The F5000 allows equipment technicians to diagnose forklift engine problems and properly tune the vehicle to achieve increased engine efficiency, performance, and fuel savings. The AQ Pro allows warehouse professionals to quickly and accurately monitor the ambient levels of dangerous gases present in warehouses and other industrial facilities. These specialized monitors include software with real-time continuous data logging and wireless Bluetooth compatibility.